Various facilities requiring large amounts of electric power (for example, a factory that uses high-voltage electric power or an office building) each hold a contract with an electric power supplier with an electric power basic charge based on the maximum amount of electric power usable by the facility. This maximum amount usable is typically called demand-contract electric power. An electric power basic charge based on demand-contract electric power applies unless electric power consumed by the facility exceeds the contract value. If electric power consumption exceeds demand-contract electric power for even 30 minutes or so, the basic charge for the subsequent months is greatly increased.
Under such circumstances, there have been proposed various techniques for monitoring electric power consumption or reducing an electric power demand amount in order to prevent electric power consumption from exceeding demand-contract electric power. In view of the circumstances of electric power supply in recent years, there have also been proposed (i) increasing an electric power charge for a time frame in which the demand for electric power is intense (demand response) or (ii) providing a monetary value to an electric power reduction capability at a facility (negawatt transaction). This has led to growing expectations for a technique for automatically controlling electric power demand at a facility.
Patent Literatures 1 and 2 each disclose, as a technique for automatically controlling electric power demand, a conventional technique of, in a case where it is predicted that the electric power consumption amount will exceed demand-contract electric power, stopping air-conditioning installations in such a manner that stoppable air-conditioning installations are stopped first. Further, Patent Literature 3 proposes a technique of forcibly controlling an illumination device with relatively large electric power consumption to reduce electric power consumption at the entire facility.
There have also been proposed techniques for performing demand control for (i) a production device at a facility such as a factory or (ii) a storage container such as a freezer at a supermarket. Patent Literature 4, for example, discloses a technique of limiting the timing of a shift of a production device from a standby state to a working state to reduce an increase in electric power consumption. Patent Literature 5 discloses a technique of selecting a controllable device from among a plurality of production devices to reduce electric power use. Patent Literature 6 discloses a technique of substantially forcibly switching the operation of a device to an electric power saving state.